Can anyone explain the difference, if any, between ‘biec’ and biegnąć’? I have never seen ‘biec’ before.

My grammar book states that both can mean ‘to run’, with perfective forms of ‘pobiec’ and ‘pobiegnąć’.

One point of interest in the book is that it then lists ‘related verbs with meanings’ and only shows suffixed versions of ‘biec’ (e.g. dobiec, obiec, nabiec etc), but no suffixed versions of ‘beignąć’. Can you also add the same suffixes to ‘biegnąć’? And if so, would they mean the same thing, e.g. would ‘dobiec’ (to reach) mean the same things as ‘dobiegnąć’?

Finally, the first version of ‘to run’ I learnt in Polish was ‘biegać’. How does this compare to the other two verbs? From an online dictionary, ‘biegnąć’ seems to mean simply to run, whereas ‘biec’ and 'biegać also mean ‘to run’ but also have alternative but similar meanings?

“Biegnąć” and “biec” mean exactly the same. A lot of sources claim that “biegnąć” is a non-standard (colloquial) form and only “biec” is correct, but not all of them seem to agree. To me, “biec” sounds better here, though the other form you mentioned—“biegać”—seems to match the context best (see the explanation below).

Though two conjugate differently, you can add the same exact suffixes to “biegnąć”, and they will also mean the same thing (e.g. “dobiegnąć” = “dobiec”).

I think the safest choice for you as a learner would be to always use “biec”, as it is much less controversial than the other form.

“Biegać” is an imperfective indeterminate verb of motion, which means it is used to talk about habits or repetitive actions.

“Biec” / “Biegnąć” is an imperfective determinate verb of motion, which means it is used to refer to one-time, continuous motion, often with a specific goal.

I didn’t specifically refer to “biegać”, but every time I mention “chodzić”, you can replace it with “biegać”, and every time I mention “iść”, you can imagine it’s actually “biec”—and it will still make perfect sense.

Thanks Adam. The book I previously referred to ‘301 Polish Verbs’ didn’t even mention that biegać was indeterminate and that biec/biegnąć were determinate.

It simply said that biec/biegnąć were imperfective and pobiec/pobienąć were perfective. Interestingly, (in light of your comments above about biegnąć being colloquial) the book then conjugates biegnąć rather than biec.

It also has a footnote (which I’ve only just noticed) that biegać is interchangeable with biec/biegnąć. Bearing in mind your comments about biegać being indeterminate and the other two being determinate, it would seem that the book has made an error, or at least not provided a full/better explanation.

And the original Polish sentence ‘Koń umie biec bardzo szybko’, also seems to be incorrect, as presumably the horse is able to run very quickly on a regular basis, in different directions, rather than one time only in a particular direction, so ‘Koń umie biegać bardzo szybko’ seems to fit the context better.